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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

26298 results found.

  1. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  2. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  3. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  4. EP260924a: EP-FXT follow-up observation
  5. Konus-Wind detection of GRB 260924A
  6. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  7. GRB 260923A: Glowbug gamma-ray detection
  8. GRB 260924A: Optical follow-up observations with Kinder
  9. GRB 260922A: Glowbug gamma-ray detection
  10. GRB 260925A: Enhanced Swift-XRT position
  11. GRB 260925A: COLIBRÍ optical upper limits
  12. GRB 260924A: Ondrejov D50 optical afterglow detection
  13. EP260924a: J-band upper limit with WINTER
  14. GRB 260924A: SVOM/GRM observation
  15. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  16. GRB 260925A: Swift detection of a burst
  17. GRB 260923A: Insight-HXMT/HE detection
  18. EP260924a: EP-WXT detection of an X-ray transient
  19. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  20. GRB 260924A: GROWTH-India Telescope optical observations
  21. GRB 260924A: Swift-BAT refined analysis
  22. GRB 260924A: NuSTAR detection of prompt emission
  23. GRB 260924A: Swift-XRT refined Analysis
  24. Konus-Wind detection of GRB 260922A
  25. GRB 260922A: NuSTAR detection of prompt emission
  26. GRB 260921A: NuSTAR detection of prompt emission
  27. GRB 260921A: SVOM/GRM observation
  28. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  29. GRB 260924A: Fermi GRB Observation
  30. Konus-Wind detection of GRB 260921A (possible merger-origin)
  31. GRB 260924A: Fermi-LAT detection of a bright burst
  32. GRB 260924A: AstroSat CZTI detection
  33. GRB 260920A: SVOM/GRM observation
  34. GRB 260924A: NOT optical counterpart confirmation
  35. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  36. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  37. GRB 260924A: Enhanced Swift-XRT position
  38. GRB 260924A: Swift detection of a burst
  39. GRB 260922A: Ondrejov D50 optical limit
  40. ATCA observations of GRB 260909A
  41. GRB 260922A: Swift-BAT refined analysis
  42. GRB 260922A: J-band upper limit with WINTER
  43. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  44. GRB 260922A: COLIBRÍ optical upper limits
  45. GRB 260922A: Swift-XRT refined Analysis
  46. GRB 260922A: Enhanced Swift-XRT position
  47. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  48. Konus-Wind detection of GRB 260810A
  49. GRB 260920A: Glowbug gamma-ray detection
  50. GRB 260918A: SVOM/ECLAIRs refined analysis
  51. GRB 260922A: SVOM/C-GFT optical upper limit
  52. GRB 260922A: Swift detection of a burst
  53. GRB 260917C: AstroSat CZTI detection
  54. GRB 260920B/EP260920b: GECAM-B detection of a burst
  55. GRB 260921A: AstroSat CZTI detection
  56. GRB 260921A: Swift-BAT refined analysis
  57. GRB 260921A: Fermi GBM Observation
  58. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  59. GRB 260917B:: SVOM/ECLAIRs refined analysis
  60. EP260920a: VLT/HAWK-I near-infrared candidate
  61. GRB 260921A: Swift detection of a burst
  62. GRB 260920A: AstroSat CZTI detection
  63. EP260920b: SVOM/VT optical observation
  64. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  65. EP260920b: COLIBRÍ optical observations
  66. EP260920b: LCO optical counterpart detection
  67. EP260920b: Einstein Probe detection of an X-ray transient
  68. EP-WXT detected a brightening of HMXB LS V +44 17
  69. EP260920a: NOT early time optical upper limits
  70. EP260920a: NOT optical upper limits
  71. EP260920a: SVOM/VT optical upper limits
  72. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  73. EP260920a: COLIBRÍ optical upper limits
  74. EP260920a: Update of the LCO optical counterpart candidate
  75. EP260920a: LCO optical counterpart candidate
  76. EP260920a: Einstein Probe detection of an X-ray transient
  77. GRB 260915A: VLT optical and near-infrared upper limits
  78. EP260917a: refined analysis of the EP-FXT observations
  79. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  80. EP260806a: Yamaguchi Interferometer radio detections
  81. EP260917a: SVOM/VT optical upper limits
  82. GRB 260918A: SVOM/C-GFT optical upper limits
  83. Fermi GBM Sub-Threshold Detection of GRB 260918A
  84. SVOM GRB260918.16: Global MASTER-Net observations report
  85. Konus-Wind detection of GRB 260916B (short/hard)
  86. GRB 260918A: SVOM/VT optical upper limits
  87. GRB 260916B: Glowbug gamma-ray detection of a short burst
  88. GRB 260918A: EP-FXT follow-up observation
  89. GRB 260917B: Mondy optical upper limit
  90. IPN triangulation of GRB 260916B (short)
  91. EP260917b: EP-WXT detection of an X-ray transient
  92. EP260917A: J-band upper limit with WINTER
  93. IPN triangulation of GRB 260810A
  94. GRB 260917B: EP-FXT follow-up observation
  95. EP260917a: COLIBRÍ optical upper limits
  96. GRB 260915A: Swift-XRT afterglow detection
  97. GRB 260918A: LCO optical upper limits
  98. EP260917a: Einstein Probe detection of an X-ray transient
  99. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  100. GRB 260918A: SVOM detection of a burst

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